The present invention relates to electronic circuit modules for carrying one or more integrated semiconductor circuit elements or "chips" thereon as well as for carrying resistance tracks and/or resistance surfaces. Specifically, the present invention relates to such an electronic circuit module which has a cooling sheet which substantially covers one lateral surface of the module for permitting improved cooling of the module by convection.
Housing-free, vertically insertable single-in-line circuit modules are generally known to those skilled in the relevant technology. Such conventional modules have carriers which may consist, for example, of synthetic film or ceramic and the carriers for such modules generally carry a series of metal terminal pins in the carrier plane which serve as external terminals for insertion of the module into a circuit board, and carry as well one or more electrical components, including at least one integrated housing-free semiconductor circuit element or chip, or a resistance track or resistance surface, and integrated circuit runs which connect the semiconductor element to respective metal terminals.
By virtue of being vertically insertable, such modules have the advantage of permitting ventilation on both sides of the carrier, and thus the components and conductor runs disposed thereon, so that the circuit module and the components carried thereon are sufficiently cooled thus permitting a relatively heavy density of components and relatively high currents to be employed on the module. This is of particular significance for reliable operation of the components especially due to the temperature dependence of resistances resulting from resistance tracks and in the integrated circuit elements. Encoder/decoder chips, for example, are known to be especially sensitive to temperature fluctuations and require that attention be paid to cooling such chips in order to insure operation within specified tolerance ranges.
The use of such vertically insertable single-in-line modules has the further advantage of improving the mechanical stability of the circuit board into which the modules are inserted as a result of the inherent stiffness and stability of the vertically-oriented carrier. Such modules, when inserted in the circuit board, function as a stiffening rib for the circuit board, particularly when such circuit modules are vertically inserted into both sides of the circuit board. This is an advantage when the circuit board experiences a high current load or is exposed to another source of heat because the vertical modules can have a length substantially greater than conventional dual in-line modules. This stiffens the circuit board over a larger area than is possible with dual-in-line modules and thus prevents arcing and sagging of the circuit board in addition to the above-mentioned improved cooling which is obtainable with such vertical modules, in contrast to dual-in-line modules.
In general, such vertical single-in-line modules have the further advantages enumerated below. The modules permit attachment of a few additional discrete electrical components such as, for example, devices for smoothing dc voltages, resistors and capacitors to the front as well as to the back of the carrier. The vertical modules permit the length of conductor runs directly at the circuit module to be relatively short, thus permitting use of the circuit module in particularly high frequency environments. Such vertical single-in-line modules further permit relatively easy testing of the integrated semiconductor circuit element carried thereon under dynamic field conditions such as, for example, at high operating frequencies. The modules of this type can be inserted and soldered to the circuit board relatively easily and can be stored in a space-saving manner before such attachment to the circuit board.
Such modules exhibit the further advantages of permitting relatively easy removal of any integrated semiconductor circuit elements on the modules which, after dynamic testing, are found to be defective in some manner and replacement of the removed component by a new or different component. Because of the absence of a housing, the semiconductor circuit elements on the vertical module are easily cooled and thus exhibit significantly decreased operational changes due to local overheating. The vertical circuit modules permit shaping of the module including through-plating between lines on opposite sides of the module, with comparative ease, particularly by means of cutting, stamping, boring and laser operations. These advantages are particularly pronounced when the carrier consists, for example, of polyimide. The conductor lines on the module can be manufactured by conventional photolithographic technology such as, for example, thin film technology. The carrier can be made very thin, thus presenting space-saving and material-saving advantages because the carrier remains substantially mechanically stable, particularly when the carrier consists of a synthetic material. The ability to construct the carrier with a small thickness also adds to the improved cooling of the components and lines on the carrier by convection, not only by air directly passing over the components, but also by air passing over the opposite side of the carrier.